It is customary to lay cable and cable bundles which extend long distances in conduit pipe. Conduit pipe is essentially a pipe provided to serve as a channel or container in which the electrical cable is permanently housed. Typically, the conduit pipe is embedded in the ground and the cable or cable bundle is pulled through the conduit by a mechanical means such as a winch. In general, the conduit pipe is provided with a diameter considerably larger than the diameter of the individual cable or cable bundle being housed by the conduit. However, large friction forces develop between the cable and the interior conduit walls which make it difficult to pull the cable through the conduit. It is customary to lubricate the cable at the entry end of the conduit to minimize the friction between the cable and the conduit walls. The cable lubricating procedure is typically accomplished manually. A man with a container of lubricant positions himself at the entry end of the conduit and continuously applies the lubricant from the container directly to the cable or cable bundle as the cable is pulled through the conduit. In practice, it has been found that the lubricant will be scraped from the cable soon after the particular section of cable has been drawn about twenty-five to thirty feet into the conduit.
It has become necessary and customary to use a winch to pull the cable or cable bundle through the conduit. However, with present state of the art techniques there is a limit to the length through which cable can be drawn. If an effort is made to draw the cable too far something will be damaged. Either the cable will break as a result of the friction forces generated between the conduit wall and the cable, the winch will reach a level whereby power is not available to overcome the friction force imposed on the cable or damage to the cable insulation or the interior walls of the conduit will occur. Regardless of which failure occurs, the failure is almost always attributable to the friction forces imposed on the cable by the conduit wall.
Therefore, it has become customary to limit the length that the cable bundle is drawn. The length limitation necessitates laying the cable in sections. At the end of each section the cable must be spliced to a subsequent cable section and the cable drawing process repeated. When the conduit pipe is underground, which is usually the case, manholes or hand holes must be dug and located at the exit end of each conduit section to facilitate splicing and drawing of cable through the next conduit section. Typically, the distances between the manholes or hand holes will vary from 300 feet to 500 feet and, in embodiments wherein tight bends occur, the distances must be much shorter.